Overdominance hypothesis suggests superiority of:
Overdominance hypothesis originating from Shull 1908 and East 1908 suggests heterozygous state at individual locus confers intrinsic superiority exceeding either homozygote due to allelic interaction. Mechanisms include formation of heterodimeric enzymes expanding substrate range, such as alcohol dehydrogenase heterodimer with broader catalytic efficiency, balanced gene expression dosage or differential interaction with regulatory proteins. Example includes MHC locus heterozygote advantage against pathogens. At quantitative trait level, overdominance may arise from pseudo-overdominance where t
Ref: East EM 1936 overdominance; Crow JF Genetics overdominance; Birchler JA Plant Cell overdominance heterosis PubMed.